<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
	</head>
	<body>
		<table>
			  <tr>
				 <td><img src="" /></td>
				 <td colSpan="3">购物简易计算器</td>
			  </tr>
			  <tr>
				 <td>第一个数</td>
				 <td colSpan="3">
					 <input type="text" id="num1" />
				 </td>
			  </tr>
			  <tr>
				 <td>第二个数</td>
				 <td colSpan="3">
					 <input type="text" id="num2" />
				 </td>
			  </tr>
			  <tr>
				 <td>
					  <input type="button" value=" + " onclick="cal('+')"/>
					<!-- <input type="button" value=" + " onclick="add()"/> -->
				 </td>
				 <td>
					 <!-- <input type="button" value=" - " onclick="cal('-')"/> -->
					 <button onclick="cal('-')">-</button>
				 </td>
				 <td>
					 <input type="button" value=" * " onclick="mul()"/>
				 </td>
				 <td>
					 <input type="button" value=" / " onclick="div()"/>
				 </td>
			  </tr>
			  <tr>
				 <td>计算结果</td>
				 <td colSpan="3">
					 <input  type="text" id="resultId" />
				 </td>
			  </tr>
		  </table>
		  <script type="text/javascript">
			function cal(type) {
			   var inputObj1 = document.getElementById('num1');
			   var inputObj2 = document.getElementById('num2');
			   var result;
			   switch(type) {
				   case '+':
					 result = parseInt(inputObj1.value) + parseInt(inputObj2.value);
				   break;
				   case '-':
					 result = parseInt(inputObj1.value) - parseInt(inputObj2.value);
				   break;
			   }
			   console.log(result);
			   var resultObj = document.getElementById('resultId');
			   resultObj.value = result;
			}
			
			
		  	function add() {
				var inputObj1 = document.getElementById('num1');
				var inputObj2 = document.getElementById('num2');
				var result = parseInt(inputObj1.value) + parseInt(inputObj2.value);
				console.log(result);
				var resultObj = document.getElementById('resultId');
				resultObj.value = result;
			}
			
			function sub() {
				var inputObj1 = document.getElementById('num1');
				var inputObj2 = document.getElementById('num2');
				var result = parseInt(inputObj1.value) - parseInt(inputObj2.value);
				console.log(result);
				var resultObj = document.getElementById('resultId');
				resultObj.value = result;
			}
		  </script>
	</body>
</html>
